1. Field of Invention
The present invention relates to an electro-optical device, a method of driving the electro-optical device and an electronic apparatus, employing an electro-optical element whose luminescent brightness is controlled by means of current, and more specifically to a technology of selecting drive modes of pixels.
2. Description of Related Art
Recently, flat panel displays (FPD) employing organic electroluminescent (EL) elements have been given attention. An organic EL element is a typical current driven element that is driven by current flowing in the element, and spontaneously emits light with a brightness corresponding to a level of the current. A driving method of an active matrix type display employing organic EL elements can be classified roughly into a voltage programming method and a current programming method.
For example, in Japanese Unexamined Patent Application Publication No. 2001-60076 relating to the voltage programming method, a pixel circuit in which a transistor (TFT 3 shown in FIG. 5 of Japanese Unexamined Patent Application Publication No. 2001-60076) for cutting off a current path is provided in the current path for supplying a driving current to an organic EL element is disclosed. The transistor is controlled into the on state in a former part of one frame period, and also is controlled into the off state in a latter part thereof. Therefore, in the former period when the transistor is turned on, and thus the driving current flows, the organic EL element emits light with a brightness corresponding to a level of the current. Further, in the latter period when the transistor is turned off and thus the driving current is cut off, since the organic EL element is forcibly put out, a black color is displayed. This technique is called ‘blinking’, and using this technique, a residual image felt by a human eye is broken off, so that it is possible to accomplish improvement in display quality of a moving picture.
For example, in Japanese Unexamined Patent Application Publication No. 2001-147659 and PCT Japanese Translation Patent Publication No. 2002-514320, constructions of a pixel circuit employing the current programming method are disclosed. In JP 659, a pixel circuit employing a current mirror circuit comprised of a pair of transistors is disclosed. In patent JP 320, a pixel circuit capable of reducing the variation of threshold voltage and the ununiformity of current in a driving transistor as a setting source of the driving current to be supplied to the organic EL element is disclosed.